Managing Sunburn: What is It and Why Does Skin Remain Red After Sunburn?

Getting sunburn is a common occurrence and can happen quite easily. Depending on factors such as the intensity of the sun, the duration of exposure, and an individual's skin type, sunburn and its effects on your skin can be severe. To protect your skin from sunburn, even while tanning, it’s crucial to use sunscreen.1,2

close up of person's eye with dry skin

What causes sunburn?

The sun emits different types of radiation, which have specific effects on your skin. UVA rays can penetrate deep into the skin, causing significant damage over time. These rays are present throughout the day and can pass through clouds and glass. UVA rays are associated with skin aging, such as wrinkles and age spots, as well as contributing to the development of certain types of skin cancer.1

UVB rays are most intense between 10 a.m. and 4 p.m. and are mostly responsible for sunburn. They also play a role in the development of skin cancer.3 UVB rays vary in intensity depending on factors such as your location, time of day, and altitude.1

How does sunburn damage your skin?

When the skin is exposed to excessive amounts of UV-radiation from the sun, or artificial sources like tanning beds, a series of reactions within the skin cells are triggered, which indirectly damage the DNA of these cells.3,4

Why does your skin turn red after sunburn, and why does sunburn hurt?

To repair damaged cells, the body initiates an inflammatory response. This response leads to the classic symptoms of sunburn, such as pain and redness, which is often accompanied by warmth and tenderness, and in severe cases swelling and blistering.4 Blisters can be very painful.

The severity of a sunburn depends on the intensity and duration of UV exposure and the level of sun protection you use, however, skin tone can also be a factor. Fair or light-skinned people can burn more easily due to less melanin in their skin, which is a protective pigment.4

Why can sunburn appear purple?

Over time, UV damage to the skin can lead to a condition known as solar purpura or actinic purpura. Solar purpura is more commonly observed in older people, as it is a long-term consequence of chronic UV damage. Approximately 12 percent of people above the age of 50 are affected.5

This condition is characterized by the appearance of small, flat, purple or red spots on the skin. They predominantly appear on areas of the body that receive significant sun exposure, such as the back of the hands, forearms, neck, and face. The blood vessels under the skin's surface weaken, which makes them more prone to rupture and leakage. As a result, small amounts of blood seep into the surrounding tissue, leading to the typical purple spots seen in solar purpura.5

What are other effects of sunburn?

Sunburn not only causes immediate discomfort, but also poses long-term risks to our health. Prolonged or intense exposure to UV radiation damages the DNA within our skin cells, increasing the likelihood of developing cancerous cells. Melanoma, the most dangerous form of skin cancer, is particularly associated with sunburn and unprotected sun exposure. If you experience five or more sunburns, or only one single blistering sunburn, it approximately doubles your risk of developing melanoma later in life.6

Sunburn also accelerates the aging process of the skin, as the harmful UV rays break down the collagen and elastin fibers that give our skin its elasticity and firmness. As a result, sunburns can lead to development of wrinkles, fine lines, and age spots.1,6

Since sunburn damages the outermost layer of the skin, it can also lead to peeling, dryness, and flakiness and in some cases, the skin may develop discoloration or uneven pigmentation.

If you have severe sunburn, and you feel cold, tired or nauseous, you may have heatstroke, so it’s important to seek medical attention.7

How to prevent sunburn?

You can effectively reduce the risk of sunburn by taking preventive measures, such as staying out of the sun during peak hours, seeking shade, and wearing protective clothing. Additionally, use a broad-spectrum sunscreen that protects against both UVA and UVB rays. Cetaphil offers a range of broad-spectrum sunscreens which are specially formulated to be gentle on the skin while providing high SPF levels to prevent sunburn and to safeguard your skin against long-term damage.

It's important to note that sun protection isn’t only essential during the summer months, but also during winter and even on cloudy days or in colder climates, as UV rays can still reach our skin and cause damage.

Why is sunscreen important in skincare?

Incorporating sunscreen into your daily skincare routine is important because it goes beyond preventing sunburn, it also helps safeguard against the signs of premature aging, age spots, and the risk of developing skin cancer.

For optimal protection, it is recommended to use a sunscreen of at least 30 SPF, and apply it 15 to 20 minutes before going out into the sun.2-4 This allows the sunscreen to be adequately absorbed by the skin. It should be reapplied every two hours or more frequently if swimming, sweating, or wiping the face.

To learn more, refer to our article How Long Does Sunscreen Last?, which provides insights into the longevity of sunscreen and offers guidance on reapplication for maximum protection.

When to apply sunscreen in skincare routine?

Sunscreen should be used daily to best protect your skin from the sun’s harmful UV rays. A good option is using a moisturizer with SPF, such as Cetaphil Daily Oil-Free Facial Moisturizer SPF 35, which can be worn underneath makeup.

If using a separate sunscreen, you should apply it as the last step of your skincare routine. Applying sunscreen generously is key to covering your skin effectively. As a general guideline, it is advised to apply to your body approximately the quantity that would fill a shot glass. For your face, a tablespoon-sized amount of sunscreen is recommended. Gently distribute the sunscreen on your skin and avoid rubbing it in excessively, as this can decrease its effectiveness.2,9

For more detailed information about when to apply sunscreen and other products in your skincare routine, please refer to What’s the Best Order to Apply Your Skincare Routine.

How to deal with sunburn?

If you experience sunburn, there are several measures you can take to alleviate the discomfort and redness associated with it. Applying a cool compress or take a cool bath can soothe the heat and reduce inflammation.10

Sunburn can also cause dry spots on your skin and peeling, so it's essential to moisturize the affected area with a gentle, fragrance-free moisturizer that includes ingredients such as glycerin.10 This is the best way to get rid of dead skin from sunburn - you shouldn’t exfoliate your skin after sunburn to try and remove peeling skin.11 Drink plenty of fluids, especially water, to replenish lost moisture and aid in healing. After experiencing sunburn, it's crucial to protect your skin from additional sun exposure.4

If your sunburn is severe or accompanied by immense pain, blistering, or fever, it's advisable to seek medical attention.

The bottom line

Prevention is key when it comes to sunburn. Wearing protective clothing, seeking shade and incorporating sunscreen into your daily skincare routine will help minimize the risk of getting a sunburn. Taking care of your skin and protecting it from the sun's harmful rays can help maintain its health and prevent long-term damage.


  1. Skincancer Foundation. UV Radiation & Your Skin. Accessed May 16, 2023
  2. Petersen B, Wulf HC. Application of sunscreen - theory and reality. Photodermatol Photoimmunol Photomed. 2014;30(2-3):96-101. doi: 10.1111/phpp.12099
  3. Gabros S, Nessel TA, Zito PM. Sunscreens And Photoprotection. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023. Available from:
  4. Guerra KC, Crane JS. Sunburn. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023. Available from: Accessed May 16, 2023
  5. Hafsi W, Masood S, Badri T. Actinic Purpura. 2023. In: StatPearls. Treasure Island (FL): StatPearls Publishing; PMID: 28846319.
  6. Skincancer Foundation. Skin Cancer Facts & Statistics. Accessed May 16, 2023
  7. Leiva DF, Church B. Heat Illness. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023. Available from: Accessed May 18, 2023
  8. American Academy of Dermatology Association. Sunscreen FAQs. Accessed May 16, 2023
  9. Sabido. Photoprotection: Review and updates. JPDS. Accessed May 16, 2023
  10. American Academy of Dermatology Association. Accessed May 16, 2023
  11. American Academy of Dermatology Association. How to safely exfoliate at home. Accessed May 18, 2023